1. Field of the Invention
The present inventive concept herein relates to wireless communication devices, and more particularly, to a wireless communication device performing a near field communication (NFC) function.
2. Description of the Related Art
A NFC function is generally performed between a card and a reader. The card may be embedded in a mobile device, such as a smart phone, to perform a noncontact electronic communication, such as a payment.
A NFC protocol is one area of conventional radio frequency identification (RFID) and may operate a terminal with a built-in tag in an active mode. As a result, the NFC protocol may perform not only a tag function but also functions associated with a reader function of reading a tag, a writer function of inputting information in a tag, and peer-to-peer (P2P) functions between terminals.
The NFC protocol is prescribed by standards in an ISO 18092 and may perform a short-distance wireless communication using a signal of various frequencies including 125 kHz, 135 kHz, and 900 MHz as well as a frequency of 13.56 MHz. The NFC protocol may support a reader such as ISO 1223 TYPEA (Mifare), TYPEB, TYPEF (Felica), and ISO 15693 TYPEV, and a card such as TYPEA, TYPEB, TYPEF, and TYPEV.
Under various NFC protocols, transmission data may be source-coded in a predetermined coding method and then transmitted through a transmission channel, and a reception unit of a reader or a card receives various kinds of transmission signals as reception data. For example, in the case of a card of ISO 14443 TYPEA, a miller coding signal may be received as reception data. In the case of a reader of TYPEA, after a Manchester coding or a BSPK coding is performed, a signal, which is subcarrier load modulated in a subcarrier frequency, may be received. Also, in the case of a card of TYPEB, an NRZ coding signal may be received, and in the case of a reader of TYPEB, after a BPSK code, a signal, which is subcarrier load modulated in a subcarrier frequency, is received. In the case of a reader of ISO 15693, after a miller code, a signal which is subcarrier load modulated in a subcarrier frequency may be received. A communication speed of the reception data may include a distribution range of 26 kpbs through 847 kbps.
In the case of a reader supporting various NFC protocols, since the reader receives a signal of various frequencies, it is important to adaptively remove a noise according to a communication frequency. In the case of removing a noise by uniformly determining a level of mask information, not only a noise but also a damping component included in a wireless signal may not be properly filtered, and a normal signal that should not be removed may be filtered. Moreover, since a damping component increases according to a level of a signal, there is a limit to increase a communication distance. Thus, it is becoming an important issue to improve performance of a wireless communication device (for example, a NFC reader, or a smart phone including the NFC reader) by filtering both a noise and a damping component.